Refrigerator defrosting means



June 16, 1953 1 F. LA PORTE 2,641,908

REFRIGERATOR DEFROSTING MEANS Filed Sept. 2, 1950 A Z- 34 HEAT-HoLo/NeEmpa/mmf? 46 6,6 4@ f MED/UMLEVEL 24 E 70 72 82 fell BY- P555 l/HL VECONO E11/SER SHUT- OFF VA L VE j; 74 64 74 az Patented June 16, 1953 n2,641,908 REFRIGERATOR DEFROSTIG vMEAN S Louis F. La Porte, Wellston,Mo., assigner to Francis L. La Porte, Burlingame, Calif.

Application September 2, 195i), Serial No. 182,971

10 Claims. (Cl. 62--115) The present invention pertains generally tomechanical refrigeration, and more particularly to improved meansadapted to defrost evaporators, or cooling units of refrigeratorsystems. Y

The defrosting problem has plagued the refrigeration industry for alongtime, and numerous attempts have been made to solve this problem inthe past.

A few of the prior art methods and apparatus have achieved a measure ofsuccess. vMost of them however, have been tried and then discarded forone reason or another, the principal reasons being that the defrostingoperations required too much time, or that the apparatus provided provedtoo complicated and so on.

The primary obj ect of this invention is to provide a method whereby thedefrosting of evaporators, whether of the iinned typaplate type, or barepipe coil construction, can be accomf plished rapidly and efficiently. l

A further object is to provide simple, rather than complicated means forattaining the primary object aforesaid.

Another object is to provide means for defrosting a drain pansimultaneously with the defrosting of an evaporator, so that water whichdrips from the latter may ow freely from the refrigerated space, as isunderstood.

Broadly, the instant invention contemplates the incorporation in aconventional refrigeration system, of a novel heat storage unitinterposed between the compressor and the evaporator; a liquid newretarding device enclosed within said unit.; a by-pass valve in thedischarge line of the compressor for diverting the gasses passingtherethrough to the evaporator in a preheated condition during adefrosting operation; and other novel features associated with theseelements for attaining the objects of the invention, as will appear.

The invention is partly diagrammatically, and partly structurallyillustrated in the accompanying drawing, and the arrangement of thevarious partsY which are combinedfto attain the objectives thereof `willbe more clearly understood from the description to follow with referenceto said drawing, in which:

Fig. 1 is a diagrammatical illustration of a conventional refrigerationsystem incorporating Athe preferred embodiment'of the presentinvenvention Fig. .3 is a'horizontal sectional view, on an en- A largedscale, taken on line 3--3 in Fig. 2, and particularly illustratingdetails of a liquid flow retarding device enclosed within the said heatstorage unit;

' Fig. 4 is a vertical sectionalfview, on a further enlarged scale,through said retarding device, the view taken on line 4-4 of Fig. 3;

Fig. 5 is a fragmentary view, similar to Fig. 2 wherein Vis illustratedan additional feature that may be included in the liquid flow retardingdevice; and y Fig. 6 is a fragmentary view similar to Fig. '1,portraying an alternate arrangement.

With particular reference now to Fig. 1, fthe conventional refrigerationsystem shown includes a compressor lil, a condenser I2, a liquidreceiver I4, an expansion valve It, and an evaporator I8. The latter isof the finned type coil construction, although itis to be understood aspreviously pointed out, that the invention is applicable to otherevaporator types.

Numeral 2 indicates a drain pan with which is associated a dischargeconduit 22. The evaporator coil is designated by numeral 24, the suctionor intake line of the compressor by numeral 25, and the compressordischarge line by numeral 28. n

The liquid line leading from the receiver tank to the expansion valve isindicated by numeral 3d. The usual shut-off valve is designated 32.

Usually as well known, the assembly including the evaporator, drain pan,and expansion valve is mounted in the space to be cooled, whereas theassembly including the compressor, condenser, and receiver is locatedremotely therefrom.

While it is taken forv granted that the operation of the conventionalsystem illustrated and thus far described is well understood,` a briefsummary is not believed to be objectionable prolix at this point.

. Thus, assuming that the temperature of the space to be cooled hasrisen above a predeter- `mined degree, "any of the well known thermalresponsive devices will cause the compressor to start. As a result,refrigerant in vapor form is withdrawn from the evaporator via line 26,

- compressed, thereupon delivered to the condenser i2 still in vaporform, and thence to receiver I4 in liquid form, via line 23.

Assuming that valve 32 is open, the refrigerant in liquid form ismetered or fed through the expansion valve it vand into the evaporatorcoil 2li. VThe ambient warmth or heat about the evap- -.-orator beingabsorbed by the refrigerant asis understood, the latter is vaporized,and in that form returned to the compressor via suction line 26 torepeat the cycle until the temperature of the space to be cooled causesthe thermal responsive device to shut off the compressor. The circuitdescribed is indicated by the broken line arrows in Fig. 1.

During these cycles of normal compressor operation, the moistureprevalent in the ambient atmosphere settles upon and is graduallytransformed into a layer or layers of frost, which increasinglyaccumulate on the external portions of the evaporator.

As is well understood, unless these layers of frost are removed fromtime to time, the eiliciency of any refrigeration system will eventuallybe reduced to a point where its operation is noneffective.

The present invention contemplates no change in the normal refrigerationsystem thus far considered. It does contemplate however, theincorporation in such system of novel means whereby the normallyemployed refrigerant or cooling agent may also serve, selectively as thedefrosting agent, without requiring cessation of normal compressoroperations.

Referring again to Fig. l, numeral 34 indicates generally a heat storageunit, 36 a by-pass valve, 38 a vapor line, and 40 a loop portion formedin the latter. The upper end of the vapor line is in communication withthe inlet portion 4| of the evaporator coil by means of a T fitting 42,as shown. f

The incorporation of the non-conventional elements `just enumeratedwill, when necessary or desired, cause the refrigeration system tosupply preheated gas vapors to the evaporator for defrosting the same ina manner to be explained later.

With particular reference now tov Figs. 2 and 3, the heat storage unit34 includes a tank 44 f containing a heat holding uid .the upper levelof which is indicated at 4S. It may be water or other selected medium.

submerged in said fluid medium, and mounted in any suitable mannerwithin container 44, is a liquid flow retarding device generallyindicated by numeral 48. Also submerged, and disposed beneath saiddevice, is a loop or coil portion 56 formed in suction line 26.Preferably but not necessarily, coil portion 50 is provided with aplurality of heat transfer fins 52 as shown. For descriptive purposes,coil 58 will sometimes be termed Vthe suction coil hereinafter.

Also submerged, and disposed in said container below suction coil 56, isa coil portion 54 formed in discharge line 28. This coil portion is alsopreferably provided with heat transfer ns designated 56. For descriptivepurposes, coil 54 will sometimes be termed the discharge coilhereinafter.

A suitable electric heating device 58 submerged in the lowerniost regionof the tank. This device may be controlled by manual or automatic means,as suggested by switch 65 in Fig. 1.

rIfhe liquid flow retarding device 4B, as will appear, is of primeimportance. As shown in the drawing it comprises a cylinder 62, closedat either end, and interposed in suction line 26 between coil 56 andthat portion of said line extending from the tank 44 to the evaporator.

In horizontally spaced relation to the inlet end wall 64 of cylinder 62,is an upper baille plate 66 which, as seen to best advantage in Fig. 4,extends downwardly to .a plane slightly above the horizontal centerlineof the cylinder` In horizontally spaced relation to the outlet end wall68 of cylinder 62, is a lower baille plate 'ES which, as also seen tobest advantage in Fig. fi, extends upwardly to a plane slightly belowthe horizontal centerline of the cylinder.

Interposed between these two bailes, and in spaced relation thereto andto one another, is a plurality of lower baille plates l2, two beingshown in the drawing. The intermediate baffles are identical with thebaffle lil', and each of the lower baffles is provided with a smallorifice or bleeder T4, preferably formed therein adjacent the low ermostportion thereof.

As portrayed in Fig. 2, delivery portion i6 of suction line 25 entersthe device 43 through wall 64, in a plane above the bottom marginal edgei8 of non-perforate baiiie 66. Near the outlet end of the device,portion B9 of said suction line depends from the lowermost region ofcylinder 62, between end wall 68 and perforate baffle l0.

It is noted that by opening valve 36, the compressor discharge gases maybe directed into line 38'. It `is also noted that said valve may bemanual'ly, mechanically or electrically operated.

In normal refrigerating operation, said valve is closed so that the highpressure refrigerant discharged from the compressor passes through thedischarge coil portion 54 of line 28, thence on to condenser l2.

In this manner, most of the heat inherent in the compressed dischargedrefrigerant is absorbed bythe fluid heat holding medium in tank 44. Thetransfer of heatr from coil 54 to the liquid is abetted by the ns 56, asis understood.

Thus, it should be manifest that during each compressor operation, heatextracted from the discharge line is stored, or accumulated, within thetank 44. It is noted that in such normal operation, the heating device58 is inoperative.

From coil 54, the thus partially liquefied refrigerant proceeds to thecondenser I2, thence to receiver I4, and thereafter, via cold liquidline 3D and metering valve I6, to the coil 24 as is understood, -but onits return to the compressor via suction line 26, it again travelsthrough the heat storage unit 34.

In other words, the refrigerant, in mingled vapor andliquid form,passing from the evaporator first enters the liquid ow retarding device48, then travels through suction coil 59, whence it continues on to thecompressor lil in completely vaporized form, as will now be explainedwith particular reference to Figs. 2 to 4.

As previously noted, the liquid flow retarding device 48 is immersedwithin container 44 in the uppermost region thereof.

As the mingled vapor and liquid body of refrigerant is drawn into device48 through portion 'i6 of suction conduit 26, it impinges upon thebaffie 66. The vapors pass quickly beneath the bottom marginal edge 'i8of said baille into coil 5G as indicated by the Fig. 2 broken linearrows, thence to compressor I6 in the usual manner.

The non-vaporized or liquid portion of the refrigerant however, iseither deflected downwardly from the baiiie 66, or drops by gravity fromportion 16 of the suction line into compartment 82 dened longitudinallyof cylinder 62 by end wall 64, and right hand intermediate lower baille72.

Bearing in mind that cylinder S2 is immersed in a body of heated fluid,a considerable quantity of this non-vaporized refrigerant is quicklytransferred into vapor form to rise and proceed onwardly through coil 59to the compressor. The

.5 residue simultaneously flows into compartment 84 via orifice 'M inthe right hand baille 12.

As the residue of non-vaporized refrigerantl flows through compartment84, a considerabler baffle 12, rthence to the suction coil 59 viaorifice 'M in baffle l0, and on to compressor lil in a now vaporizedstate. l

From the foregoing, it should be evident that the device 48, inconjunction with the coil t, pro vides for the complete vaporization ofthe refrigerant enroute to the compressor from the evaporator. Theorifices I4 prevent the flow of any liquid slugs to the compressor, theorice in the baffle 1B preferably being of a more minute diam* eter thanthe others.

Assuming now that the evaporator requires de frosting, valve 36 isopened whereby gases from both the compressor and the condenser willflow into line 38. Opening of valve 35, starts the defrosting cycle,which continues as long as said valve is open.

That is to say, the cycle continues uninter ruptedly until defrosting iscomplete, whereupon closing of valve 36 will again place the system incondition to resume normal refrigeration operation.

The defrosting circuit is indicated by. full line arrows in Fig. l, andwill be further described with reference also to Fig. 2. Aftermanipulation of valve 36 to open or defrost position, the high pressuregases from the compressor pass through the heat storage unit via line28, coil 515, valve 3G,

line 38, loop 4t, 'l' 42 and into the evaporatorr .coil 24. o

As the preheated'gas circulates through the from and into coil 54contain comparatively little heat. As these vapors continue to advancethrough said coil toward the evaporator, addiloop 40 and coil 24, it ispartially condensed. That is to say, the heat inherent in the vapors istransferred to the evaporator and the drain pan whereby to melt frostwhich had accumulated thereon.

`As a result, the refrigerant leaves the coil in a v v partially liquidstate and proceeds via suction line 2t to the device A8 in the heatstorage unit.

j As previously explained in detail, passage of the refrigerant throughheat storage unit 34 cornpletely reevap-orates the same. Thus it leavessaid vunit and proceeds via line 26 to the compressor in the form ofvapors, to repeat the cycle until the defrosting operation is brought toan end. Should it be desired to accelerate the defrostn ing operation,additional heat may be supplied to y the liquid in container 44 by theelectrical heating device 58. In that event, switch 6D may be closedprior to manipulating the valve 35 to defrost position.

It is notedthat discharge coil 54 has a dual role. In other words,during normal refrigerating cycles, said coil serves to supply heat tothe storage tank; during defrosticycles, said coil servesto extract heattherefrom and transfer same to the vapors enroute to the evaporator fromthe compressor. v y

That is to say, when theesystem is operating normally, each time thecompressor goes on, refrigerant vapor is compressed and in passingthrough said coil on its Way to the condenser, it supplies heat to theluid within tank d'3.

. However, immediately following the opening oi by-pass valve 36,pressures within the entire sys,-

tem tend to equalize. As a result, the compressor at such time functionsin themanner of a circulating pump, so that the gases dischargedtheretional heat is absorbed by them from-the previously stored heat inthe tank, augmented if desired, by heat generated by the device 58.

In other Words, during normal refrigerating cycles, coil 513 suppliesheat to the tank for storage; during defrosting cycles, said coilwithdraws previously stored heat fromv the tank.

From theiforegoing, it should be manifest that the present inventionVprovides a simple, highly eflicient method and means for rapiddefrosting operations without turning off the compressor.

It should also be evident, that the incorporation A in a conventionalrefrigerating system of the heat storage unit 34, and particularly theliquid ow retarding device d8 thereof, will increase the eiciency of thesystem in normal operation.

The invention obviously admits of modifican tions without departing fromthe principles there of. For example, in some installations, the coil 4Bbeneath the drain pan may be eliminated.

And, as shown in Fig. 5, the device d8 may be provided'with a vapor tube88, one end of which enters cylinder 62 at a high level, the other endbeing connected into suction line 2S by T fitting Sli outside the tank.

With this arrangement, some of the vapors will by-pass coil 59. It mayalso not be necessary to immerse the liquid flow retarder 48 in theheatholding medium, as this View indicates.

The invention also contemplates heating the fluid in tank de by meansother than the dircharge line.' In that case, and with reference to Fig.6, Vit is noted that compressor discharge line ZSleads both to coil 54and t0 condenser l2, there being a T fitting 92 interposed in the lineshown.

Numeral 9d indicates diagrammatically a coil submerged in theheat-holding medium. Either steam or hot water may vbe circulatedthrough this coil to maintain the uid Within tank da at desiredtemperature.

Again, coil 94 may be dispensed with, and the medium heated entirely byone or more electrical heating devices 5E, The invention also conter-.iuplates, assuming the iluid in tank 4l! to be watery that heat may besupplied by providing Jfor a constant or intermittent flow of hot waterinto and thereafter outl of the tank.

, Except for the'slight differences pointed out, vthe system illustratedin Fig. e is identical' with shown in Fig. l, and the same referencenumerals'have been appliedto corresponding parts. 'Obviously howeverwith this arrangement, the sole purpose of coil 54! is to preheat thegas vapors enroute to the evaporator coil during a defrost operation.

In normal operation the discharge gas travels directly to the condenser,and thence through the system and back to the compressor as in the lembodiment. Y

During a defrost cycle, with valve 36 open to line 33, the discharge gastravels onward to the evaporator coil 24 and thence through the systemand back to the compressor in the identical manner described atlengthhereinbefore with respect maintaining said liquid at a hightemperature, a :rst coil submerged in the liquid and formed in thedischarge line of said compressor, a second coil submerged in the liquidand formed in the suction line of said compressor, a flow retardingdevice of the character described interposed in the suction line withinthe container-.between the second coil and the evaporator for vaporizingthe refrigerant passing therethrough from said evaporator, a vapor linein communication at one end with the inlet portion of the evaporatorcoil, and a normally closed valve on the other end of the vapor line andin communication with the compressor discharge line for diverting thenormal flow of discharge gases into said vapor line.

2. In combination with a refrigeration system including a compressor, acondenser, and an evaporator, means for defrosting said evaporatorwithout turning oil the compressor, said means including a container atleast partially lilled with a quantity of liquid, heatsupplying meansfor maintaining said liquid at a high temperature, a first coilsubmerged in the liquid and formed in the discharge line of saidcompressor, a second coil submerged in the liquid and formed in thesuction line of said compressor, a flow retarding device of thecharacter described intern posed in the suction line within thecontainer between `the second coil and the evaporator for vaporizing therefrigerant passing therethrough from said evaporator, and a valve fordivertingv the normal flow of discharge gases from said compressor to avapor line in communication at its lower' end with said valve, and atits upper end with the inlet portion of the evaporator coil.

3. In combination with a refrigeration system including a compressor, acondenser, and an evaporator, means for defro'sting said evaporatorwithout turning off the compressor, said -means including a container atleast partially filled with a quantity of liquid, heat-supplying meansfor maintaining said liquid at a high temperature, a first coilsubmerged in the liquid and formed in the discharge line of saidcompressor, a plurality of heat transfer fins on said coil, a secondcoil submerged in the liquid and formed in the suction line of saidsystem, a plurality of heat transfer fins thereon, a flow retardingdevice of the character described interposed in the suction line withinthe container between the second coil and the evaporator for vaporizingthe refrigerant passing therethrough from said evaporator, and a valvefor diverting the normal flow of discharge gases from said compressor toa vapor line in communication at its lower end with said valve, and atits upper end with the inlet portion of the evaporator coil.

4. In combination with a refrigeration system including a compressor, acondenser, and an evaporator, means for defrosting said evaporatorwithout turning off the compressor, said means including a container atleast partially filled with a quantity of liquid, heat-supplying meansfor maintaining said liquid at a high temperature, a first coilsubmerged in the liquid and formed in the discharge line of saidcompressor, a plurality of heat transfer fins on said coil, a secondcoil Y submerged in the liquid and formed in the suction line of saidsystem, a plurality of heat transfer fins thereon, a now retardingdevice of the character described interposed in the suction line withinthe container between the second coil and the evaporator for vaporzingthe. refrigerant passing therethrough from said evaporaton a valve fordiverting the normal flow of discharge gases from said compressor to avapor line in communication at its lower end with said valve, and at itsupper end with the inlet portion of the evaporator coil, and anauxiliary electrical heating device submerged in the liquid beneath therst coil aforesaid.

5. In combination with a refrigeration system including a compressor, acondenser, and an evaporator with associated drain pan, means fordefrosting said evaporator and pan without turning off the compressor,said means including a container at least partially filled with aquantity of liquid, heat-supplying means for maintaining said liquid ata high temperature, a rst coil submerged in the liquid and formed in thedischarge line of said compressor, a plurality of heat transfer ns onsaid coil, a second coil submerged in the liquid and formed in thesuction line of said compressor, a plurality of heat transfer finsthereon, a flow retardingvdevice of the charac ter described interposedin the suction line within the container between the second coil andevaporator for vaporizing the refrigerant passing therethrough from saidevaporator, and a valve for diverting the normal fiow of discharge gasesfrom said compressor to a vapor line in communication at its lower endwith said valve, and at its upper end with the inlet portion of theevaporator coil, said vapor line having formed therein a loop portionadapted to engage a portion of said drain pan.

6. In combination with a refrigeration system including a compressor, acondenser, and an evaporator, means for temporarily converting a portionof said system into a defrosting system, said means including a heatstorage unit in the form of a sealed container at least partially filledwith a quantity of liquid maintained at a high temperature, a firstfinned coil formed in the compressor discharge line and submerged insaid liquid, a second finned coil formed in the compressor suction lineand submerged in the liquid, a flow retarding device of the characterdescribed interposed in the suction line aforesaid between the secondcoil and the evaporator also submerged in the liquid for vaporizing therefrigerant passing through said device from said evaporator, and avalve in communication with the compressor discharge line for divertingthe discharge gases which normally flow from the compresor via said linetoward the condenser into a conduit leading from said valve to the inletportion of the evaporator coil.

7. In combination with a refrigeration system including a compressor, acondenser, and an evaporator, means for temporarily converting a portionof said system into a defrosting system, said means including a heatstorage unit in the form of a sealed container at least partially filledwith a quantity of liquid, a first finned coil formed in the compressordischarge line and submerged in said liquid for normally transferringthereto the heat inherent in the hot gases passing through the coil, anauxiliary electrical heating device submerged in the liquid below saidcoil to further heat said liquid when desirable, a second finned coilformed in the compressor suction line and submerged in the liquid, aflow retarding device of the character described interposed in thesuction line aforesaid between the second coil and the evaporator alsosubmerged in the liquid for vaporizing the refrigerant passing throughsaid device from said evaporator, and a valve in communication with thecompressor discharge line for diverting the discharge gases which nor-9. The defrosting means set forth inl claim 1 l wherein theheat-supplying means for maintaining said liquid at a high temperatureincludes a coil submerged in said liquid, said coil having an inletportion and an outlet portion each projecting through and beyond saidcontainer whereby hot water may be circulated through said coil.

10.v In combination with a refrigeration system including a compressor,a condenser, and an evaporator, means for defrosting said evaporatorwithout turning off the compressor, said means including a container atleast partially filled with a quantity of liquid, heat-supplying meansfor maintaining said liquid at a high temperature, a first coilsubmerged in the liquid and formed in the discharge line of saidcompressor, a second coil submerged in the liquid and formed in thesuction line of said compressor, a flow retarding device of thecharacter described interl0 posed inthe suction line within thecontainer between the second coil and the evaporator for vaporizing therefrigerant passing therethrough from said evaporator, a vapor tubeftheupper end of which is in iiuid communication with said flow retardingdevice above the horizontal centerline of the latter and the lower endof which is connected into the suction line outside the container, and aValve for diverting the normal flow of discharge gases from saidcompressor to a vapor line in communication at itsl lower end with saidvalve, and at its upper end with the inlet portion of the evaporatorcoil.

Louis F. LA PORTE.

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